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I want to design PCB of a GSM module. Inside a GSM module there is a place to put a (mobile cellular ) SIM card. And then this GSM module can send SMS text messages to different phone numbers.

Basically I want to design a breakout board containing the different chips required in a GSM module. I was able to find a schematic of a GSM module (containing chip SIM900) on the following website:

https://www.itead.cc/wiki/SIM900/SIM900A_GSM/GPRS_Minimum_System_Module

Here is the schematic download link in the above web page: ftp://imall.iteadstudio.com/Modules/IM120525010_SIM900_module/SCH_IM120525010_GPRS_Module.pdf

OK i I now have the schematic but I am unable to find the individual components (to buy) present in the schematic. Why so ? (Question 1) For example I am unable to find SIM900 standalone chip.

I want to have my own minimalist design of a GSM module because I want to integrate this GSM module with other chips on a single PCB. How can I do that? Is it feasible ? (Question 2)

I can buy that complete GSM module from the market. The complete 'connected' GSM module breakout board containing the SIM900 chip. Yes I can do that. But actually I want to integrate the GSM module board with another different arduino board. So I will need to buy these 2 boards.

But, I want to lower the cost and have my own design of arduino and GSM on a SINGLE PCB. That is why I need to have my own design of GSM module. And thats why I am searching for it.

Let me know if you need any more clarification.

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  • \$\begingroup\$ That's not realistically possible, no. At best you could get a complete modem in solder down module form but as you're likely to have issues with the first design stick with something connectorized where a slight mistake won't ruin it. \$\endgroup\$
    – Chris Stratton
    Aug 14, 2020 at 10:46
  • \$\begingroup\$ @ChrisStratton Are you telling that I can buy that complete GSM module from the market? The complete 'connected' GSM module containing the SIM900 chip? Yes I can do that. But actually I want to integrate the GSM module board with arduino board. So I need to buy these 2 boards. But, I want to lower the cost and have my own design of arduino and GSM on a SINGLE PCB. \$\endgroup\$
    – AlphaParticle
    Aug 14, 2020 at 10:50
  • \$\begingroup\$ In some situations it’s actually cheaper to integrate a module than just a chip, especially if you’re not dealing with very large volumes. Also antenna tuning is an art, and it may take you a while and a bit of money to get it right. Likewise for EM issues for certification. But if you really want to go that way, the SIM900 is available from some distributors, check on digipart for example. \$\endgroup\$
    – jcaron
    Aug 14, 2020 at 13:53
  • \$\begingroup\$ You can buy a SIM900, you cannot make one. I wouldn't recommend trying to solder such a module on a board until you have more experience at both SMD design and soldering as mistakes will likely be unfixable. The process of buying stuff is off topic anyway. \$\endgroup\$
    – Chris Stratton
    Aug 14, 2020 at 14:13

1 Answer 1

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  1. The reason is usually that the manufacturer doesn't have an arrangement with distributors (eg. Farnell, Digikey) so you have to buy from them directly. They do not care about someone who wants to buy one or two, you usually have to be talking about regular orders of 1000s of pieces for them to bother with you. Clearly ITEAD are able to order a large enough quantity from Simcom. Additionally the SIM900 is at end of life, they suggest using the SIM800 instead.
  2. Is it feasible? Yes, but... Guessing from the level of your question (apologies if I'm mistaken), you wouldn't have the experience/tools to be able to design a good product. I would suggest getting a module with the antenna in place, and just the digital control pins (and power) brought out.
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  • \$\begingroup\$ Thank you for telling me about SIM800. Regarding Point 2: Any small/brief comments on how to design my own GSM module (since it is after all feasible :-) ). I have some experience with KiCAD. I would appreciate further tips/comments on this. I want to ATTEMPT designing it. \$\endgroup\$
    – AlphaParticle
    Aug 14, 2020 at 11:02
  • \$\begingroup\$ @NeedSomeLuck just to consistent on terminology, the GSM module is the SIMx00 (you definitely could not build this yourself); this is then be placed on a carrier (such as the ITEAD board you linked). To design a carrier board, I suggest copying the schematics, cutting out what you think you don't need, and copy the important parts of the layout (mainly the antenna). Be warned though, because you don't know the details of their actual implementation (PCB stack up etc), this is not guaranteed to work. Good luck :) \$\endgroup\$
    – awjlogan
    Aug 14, 2020 at 12:36

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